USB only provides 5 VDC, so any USB adapter will have the correct voltage. Now they might not provide enough current. Many phone adapters have less than 1 amp out, which is probably not enough for the Stick. But I'd have to pull my 3600 out of my suitcase to see what it's adapter rated at. I can do that when I get home if someone doesn't offer it here first.
Roku Community Streaming Expert
Help others find this answer and click "Accept as Solution." If you appreciate my answer, maybe give me a Kudo.